Speaking to Uproxx, McQuarrie mentioned the night that Tom Cruise pitched his take on the sequel:

We went out to dinner when we were making Mission and Tom said, “I have an idea for the sequel to Edge, and I said, “I don’t want to fucking hear it. I do not want to know!” And he pitched the idea to me and he finished pitching it, I was like, “Goddammit, why did you do that?”

It certainly sounds like Cruise's pitch may have gotten McQuarrie's wheels turning, but with so many big names needed in order to proceed, Christopher McQuarrie seems skeptical that a sequel will actually come to fruition:

It all comes down to Warner Bros. and Doug Liman and Emily Blunt saying yes. The idea is there. At worst, it’s the kernel of an idea – which is, on one hand, great, but on the other hand, I know what a nightmare that is. I know that I’ll be in the void trying to figure that out. And even then when it came out in the press after Tom had mentioned it, right away, there were people on social media saying, “Don’t do it, it should never have a sequel, etc., etc.” And I’m just laughing because I’m like, “You guys don’t even know what we are talking about! You have no idea!”

McQuarrie also commented on the difficulties of marketing EDGE OF TOMORROW and that if he were to write a sequel he would make sure that it would be an easier sell to the general public. Wanting a sequel to EDGE OF TOMORROW isn't exactly high on my list of priorities but as the man said, I have no idea what their sequels ideas consist of so I can't pass any judgement on it; but if it's a worthwhile idea which gives us a film just as entertaining as the first, why the hell not?